Methods and apparatus for surface wetting control

ABSTRACT

For surface wetting control, an apparatus can expel fluid from a droplet on a surface using a transducer mechanically coupled to the surface. A first area of the surface can have a first wettability for the fluid, and a second area of the surface can have a second wettability for the fluid. The first wettability of the first area of the surface can be greater than the second wettability of the second area of the surface. The first area and the second area can have a patterned arrangement.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.15/492,433 filed Apr. 20, 2017, which is incorporated herein byreference.

TECHNICAL FIELD

This description relates generally to surface wetting, and moreparticularly to methods and apparatus for surface wetting control.

BACKGROUND

Unfortunately, a number of motor vehicle deaths appears to be increasingevery year. This trend is caused by various reasons, including anincrease in the driving population. Also, more engineering effort isneeded to reduce risk of death or serious injury in automobiles. Inaddition to avoiding risks to drivers and passengers, more robustobstacle and collision avoidance systems are required to reduce the highcost of damage to automobiles and other property due to collisions.

Manufacturers can incorporate new technologies into new automobiles at areasonable cost. Some promising technologies may help to improveobstacle and collision avoidance systems, such as digital camera basedsurround view and camera monitoring systems. In some cases, cameras canincrease safety by mounting in locations that give a driver access toalternative perspectives, which are otherwise diminished or unavailableto the driver's usual view through windows or mirrors. While mountingone or more cameras for alternative views can provide many advantages,some challenges may remain.

SUMMARY

Mounting cameras for alternative views may expose optical surfacesassociated with cameras to hazards such as fluid droplets (e.g., waterdroplets) that can interfere with visibility of such alternative views.The described examples include methods and apparatus for surface wettingcontrol. In certain described examples, an apparatus can expel fluidfrom a droplet on a surface using a transducer mechanically coupled tothe surface. A first area of the surface can have a first wettabilityfor the fluid, and a second area of the surface can have a secondwettability for the fluid. The second wettability of the second area ofthe surface can be greater than the first wettability of the first areaof the surface. The first area and the second area have a patternedarrangement.

Other described examples include a method to operate upon a droplethaving a first size. For example, the first size of the droplet can bereceived to overlap a first area of a surface and a second area of thesurface. The first area can have the first wettability for fluid of thedroplet, and the second area of the surface can have the secondwettability for the fluid, in which the second wettability of the secondarea of the surface is greater than the first wettability of the firstarea of the surface. A first signal including a first frequency can begenerated to be coupled with the transducer mechanically coupled to thesurface. The transducer can be activated at the first frequency bycoupling the first signal with the transducer. The droplet can bereduced using the first frequency of the first signal from the firstsize to a second size.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is partial block diagram of a system according to an embodimentincluding an apparatus that can expel fluid from a droplet on an opticalsurface under surface wetting control.

FIG. 2A is a simplified cross sectional view according to an embodimentof the droplet received at the optical surface (e.g., located on theoptical surface) under surface wetting control.

FIG. 2B is a cross sectional view according to an embodiment, similar toFIG. 2A, but showing movement of the droplet at the optical surface(e.g., on the optical surface) under surface wetting control.

FIG. 2C is a cross sectional view according to an embodiment, similar toFIG. 2B, but showing vibration to expel fluid from the droplet at theoptical surface (e.g., on the optical surface) under surface wettingcontrol.

FIG. 3A is a simplified perspective view according to an embodiment,similar to FIG. 2A showing the droplet received at the optical surface(e.g., located on the optical surface) under surface wetting control.

FIG. 3B is a perspective view according to an embodiment, similar toFIG. 3A, but showing movement of the droplet at the optical surface(e.g., on the optical surface) under surface wetting control.

FIG. 3C is a perspective view according to an embodiment, similar toFIG. 3B, but showing vibration to expel fluid from the droplet at theoptical surface (e.g., on the optical surface) under surface wettingcontrol.

FIG. 4A is a simplified cross sectional view according to an embodimentof second and third droplets received at the optical surface (e.g.,located on the optical surface) under surface wetting control.

FIG. 4B is a cross sectional view according to an embodiment, similar toFIG. 4A, but showing movement of the second and third droplets at theoptical surface under surface wetting control.

FIG. 4C is a cross sectional view according to an embodiment, similar toFIG. 4B, but showing vibration to expel fluid from the second and thirddroplets at the optical surface under surface wetting control.

FIG. 5A is a simplified cross sectional view according to anotherembodiment of the droplet received at the optical surface (e.g., locatedon the optical surface) under gradient control of surface wetting.

FIG. 5B is a cross sectional view according to an embodiment, similar toFIG. 5A, but showing movement of the droplet at the optical surface(e.g., on the optical surface) under gradient control of surfacewetting.

FIG. 5C is a cross sectional view according to an embodiment, similar toFIG. 5B, but showing vibration to expel fluid from the droplet at theoptical surface (e.g., on the optical surface) under gradient control ofsurface wetting.

FIG. 5D is a cross sectional view according to another embodiment,similar to FIG. 5B, but with first areas much larger than the dropletand with a second area much smaller than the droplet.

FIG. 5E is a simplified view similar to what is shown in FIG. 1, butwith first and second areas shown much smaller than the droplet.

FIG. 6A is a diagram of impedance versus frequency for an exampleultrasonic transducer mechanically coupled to an example optical surfaceaccording to an embodiment.

FIG. 6B is a diagram of example droplet size reduction versus frequencyaccording to an embodiment.

FIGS. 7A-7B show a flowchart representative of example machine readableinstructions that may be executed to implement the example system toexpel fluid from the droplet under surface wetting, according to anembodiment as shown in the example of FIG. 1.

FIG. 8 is a block diagram of an example processing platform capable ofexecuting the machine readable instructions of FIGS. 7A-7B to implementthe example system to expel fluid from the droplet under surface wettingcontrol, according to an embodiment as shown in the example of FIG. 1.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

U.S. Pat. Nos. 10,596,604 and 10,384,239 are incorporated herein byreference.

FIG. 1 is partial block diagram of a system 100 that can expel fluid(e.g. water) from a droplet 102 from an optical surface 104 using anultrasonic transducer 106 mechanically coupled to the optical surface104. This apparatus can expel fluid from the droplet by atomizationunder wettability control from the optical surface 104. For example, theultrasonic transducer 106 can be a piezoelectric ultrasonic transducer106 including a piezoelectric material (e.g., lead zirconate titanatePZT or niobium doped lead zirconate titanate PNZT.) Epoxy can be usedfor the mechanical coupling of the ultrasonic transducer 106 with theoptical surface 104. The fluid droplet 102 can be disposed on theoptical surface 104, and can be coupled with the ultrasonic transducer106 through the optical surface 104. In the example of FIG. 1, theultrasonic transducer 106 mechanically coupled to the optical surface104 has first and second resonant frequency bands.

A first area 108A of the optical surface 104 can have a firstwettability for the fluid, and a second area 110A of the optical surface104 can have a second wettability for the fluid. The first area 108A isshown in the example of FIG. 1 using stippling. The second area 110A isshown in the example of FIG. 1 using cross hatching.

The second wettability of the second area 110A of the optical surface104 can be greater than the first wettability of the first area 108A ofthe optical surface 104. For example, a hydrophobic coating can beapplied to the first area 108A, so as to limit the wettability of thefirst area 108A. For example, application of the hydrophobic coating tothe second area 110A can be avoided, so that second wettability of thesecond area 110A of the optical surface 104 can be greater than thefirst wettability of the first area 108A.

The first area 108A and the second area 110A can have a patternedarrangement, as shown in the example of FIG. 1. Further, the first area108A can be a plurality of first areas 108A, 108B, 108C, 108D, 108E,108F, 108G, 108H, 108I, 108J, 108K, 108L. The second area 110A can be aplurality of second areas 110A, 110B, 110C, 110D, 110E, 110F, 110G,110H, 110I, 110J, 110K, 110L, 110M. A patterned arrangement of the firstand second areas can be an alternating arrangement, as shown for examplein FIG. 1, in which a member of the first areas (e.g., first area 108A)can be interposed between a pair of members of the second areas (e.g.,pair of second areas 110A, 110B). In the alternating arrangement shownfor example in FIG. 1, a member of the second areas (e.g., second area110A) can be interposed between a pair of members of the first areas(e.g., pair of first areas 108A, 108B). The first area (e.g., first area108A) and the second area (e.g., second area 110A) can be adjacent toone another in the patterned arrangement, as shown in the example ofFIG. 1. A first edge 108AE of the first area (e.g., first area 108A) canbe proximate to a second edge 110AE of the second area (e.g., secondarea 110A) in the patterned arrangement.

Accordingly, the patterned arrangement of the first and second areas canbe an alternating grid arrangement, for example a checkerboard likesquare grid arrangement as shown for example in FIG. 1. In otherexamples the optical surface 104 can be circular. For example, thepatterned arrangement of the first and second areas can be analternating concentric circular grid arrangement. For example, ratherthan the checkerboard like square grid arrangement shown in the exampleof FIG. 1, a dart board like concentric circular grid arrangement can beused in the patterned arrangement of the first and second areas.

As shown in the example of FIG. 1, a signal generator 112 can be coupledwith the ultrasonic transducer 106. The signal generator 112 cangenerate a first signal 114 including a first frequency 116 to reducethe fluid droplet from a first size 102A to a second size 102B, and togenerate a second signal 118 including a second frequency 120 to reducethe fluid droplet from the second size 102B to a third size 102C. In thedrawings: the first droplet size 102A is representatively illustratedusing a dash-dot-dot-dash line style; the second droplet size 102B isrepresentatively illustrated using a dash-dot-dash line style; and thethird droplet size 102C is representatively illustrated using solid linestyle.

The first frequency 116 to reduce the fluid droplet from the first size102A to the second size 102B can be higher in frequency than the secondfrequency 120 to reduce the fluid droplet from the second size 102B tothe third size 102C. The first frequency 116 of the first signal 114 iswithin the first resonant frequency band of the ultrasonic transducer106 mechanically coupled to the optical surface 104. In some examples,the first frequency 116 of the first signal 114 can be a first sweep offrequencies (e.g., a first frequency sweep) within the first resonantfrequency band of the ultrasonic transducer 106 mechanically coupled tothe optical surface 104. The second frequency 120 of the second signal118 is within the second resonant frequency band of the ultrasonictransducer 106 mechanically coupled to the optical surface 104. In someexamples, the second frequency 120 of the second signal 118 can be asecond sweep of frequencies (e.g., a second frequency sweep) within thesecond resonant frequency band of the ultrasonic transducer 106mechanically coupled to the optical surface 104. The first frequency 116of the first signal 114 can be different than the second frequency 120of the second signal 118. The first frequency sweep can be differentthan the second frequency sweep. The first resonant frequency band canbe different than the second resonant frequency band.

As shown in the example of FIG. 1, the first area 108A can have a firstwidth dimension W108A that can be greater than a corresponding widthW102A of the first size 102A of the droplet 102. The first widthdimension W108A of the first area 108A can be greater than acorresponding width W102B of the second size 102B of the droplet 102.The first width dimension W108A of the first area 108A can be greaterthan a corresponding width W102C of the third size 102C of the droplet102.

Similarly, as shown in the example of FIG. 1, the second area 110A canhave a first width dimension W110A that can be greater than acorresponding width W102A of the first size 102A of the droplet 102. Thesecond width dimension W110A of the second area 110A can be greater thana corresponding width W102B of the second size 102B of the droplet 102.The second width dimension W110A of the second area 108A can be greaterthan a corresponding width W102C of the third size 102C of the droplet102.

FIG. 2A is a simplified cross sectional view according to an embodimentof the droplet 102 received at the optical surface 104 (e.g., located onthe optical surface 104) under surface wetting control. FIG. 2B is across sectional view according to an embodiment, similar to FIG. 2A, butshowing movement of the droplet 102 at the optical surface 104 undersurface wetting control. FIG. 2C is a cross sectional view according toan embodiment, similar to FIG. 2B, but showing vibration to expel fluidfrom the droplet 102 at the optical surface 104 under surface wettingcontrol.

The first areas 108A, 108B are shown in the examples of FIGS. 2A-2Cusing stippling. The second areas 110A, 110B, 110C are shown in theexamples of FIGS. 2A-2C using cross hatching. The examples of FIGS.2A-2C show the alternating patterned arrangement in cross sectional viewof the first areas (e.g., first areas 108A, 108B) and the second areas(e.g., second areas 110A, 110B, 110C). For example, a member of thefirst areas (e.g., first area 108A) can be interposed between a pair ofmembers of the second areas (e.g., pair of second areas 110A, 110B).Another member of the first areas (e.g., first area 108B) can beinterposed between another pair of members of the second areas (e.g.,pair of second areas 110A, 110C). A member of the second areas (e.g.,second area 110A) can be interposed between a pair of members of thefirst areas (e.g., pair of first areas 108A, 108B).

In the examples of FIGS. 2A-2C, the second wettability of the secondareas 110A, 110B, 110C of the optical surface 104 can be greater thanthe first wettability of the first areas 108A, 108B of the opticalsurface 104. For example, the hydrophobic coating can be applied to thefirst areas 108A, 108B so as to limit the wettability of the first areas108A, 108B. For example, application of the hydrophobic coating to thesecond areas 110A, 110B, 110C can be avoided, so that second wettabilityof the second areas 110A, 110B, 110C of the optical surface 104 can begreater than the first wettability of the first areas 108A, 108B.

The second wettability of the second areas 110A, 110B, 110C of theoptical surface 104 is sufficiently greater than the first wettabilityof the first areas 108A, 108B of the optical surface 104 to cause atleast some movement of the droplet 102 from the first area 108A to thesecond area 110A. FIG. 2A shows droplet 102 partially received at (e.g.,partially located on) the first area 108A having the first wettabilityand partially received at (e.g., partially located on) the second area110A having the second wettability. Since the second wettability isgreater than the first wettability, a notional block arrow is shown inFIG. 2A to depict movement of the droplet 102 from the first area 108Ato the second area 110 A. Further, comparison of FIG. 2A to FIG. 2Bshows that in FIG. 2B the droplet has moved to the second area 110A,from being partially received at (e.g., partially located on) the firstarea 108A and partially received at (e.g., partially located on) thesecond area 110A in FIG. 2A.

The ultrasonic transducer 106 described above with respect to FIG. 1 canexcite a vibrational mode of the optical surface 104 having a greaterextent of vibration at the second area 110A than at the first area 108A.For example, FIG. 2C shows the vibrational mode of the optical surface104 having a first extent of vibration (e.g., EXTENT1) at the first area108A and having a second extent of vibration (e.g., EXTENT2) at thesecond area 110A. As shown in the example of FIG. 2C, the second extentof vibration (e.g., EXTENT2) at the second area 110A is greater than thefirst extent of vibration (e.g., EXTENT1) at the first area 108A. Forexample, the relatively greater wettability of the second area 110A canmove the droplet 102, where the relatively greater extent of vibration(e.g., EXTENT2) can expel fluid from the droplet by atomization. Forexample, regions of greatest wettability (e.g. second area 110A) can beplaced at locations of largest vibration amplitude. In the example ofFIG. 2C, a notional upward block arrow is used to depict the relativelygreater extent of vibration (e.g., EXTENT2) expelling fluid from thedroplet 102 by atomization.

FIG. 3A is a simplified perspective view according to an embodiment,similar to FIG. 2A showing the droplet 102 received at the opticalsurface 104 (e.g., located on the optical surface 104) under surfacewetting control. FIG. 3B is a perspective view according to anembodiment, similar to FIG. 3A, but showing movement of the droplet 102at the optical surface 104 under surface wetting control. FIG. 3C is aperspective view according to an embodiment, similar to FIG. 3B, butshowing vibration to expel fluid from the droplet 102 at the opticalsurface 104 under surface wetting control. The first areas are shown inthe examples of FIGS. 3A-3B using stippling. The second areas are shownin the examples of FIGS. 3A-3B using cross hatching. The examples ofFIGS. 3A-3B show the alternating patterned arrangement in perspectiveview of the first areas and the second areas.

The second wettability of the second area 110A of the optical surface104 is sufficiently greater than the first wettability of the first area108A of the optical surface 104 to cause at least some movement of thedroplet 102 from the first area 108A to the second area 110A. FIG. 3Ashows droplet 102 partially received at (e.g., partially located on) thefirst area 108A having the first wettability and partially received at(e.g., partially located on) the second area 110A having the secondwettability. Since the second wettability is greater than the firstwettability, a notional block arrow is shown in FIG. 3A to depictmovement of the droplet 102 from the first area 108A to the second area110 A. Further, comparison of FIG. 3A to FIG. 3B shows that in FIG. 3Bthe droplet has moved to the second area 110A, from being partiallyreceived at (e.g., partially located on) the first area 108A andpartially received at (e.g., partially located on) the second area 110Ain FIG. 3A.

For example, the relatively greater wettability of the second area 110Acan move the droplet 102, where the relatively greater extent ofvibration can expel fluid from the droplet by atomization. In theexample of FIG. 3C, a notional upward block arrow is used to depict therelatively greater extent of vibration expelling fluid from the droplet102 by atomization. For ease of viewing, depiction of vibration issimplified in FIG. 3C, and both the second area 110A and the droplet 102are depicted using a stippled line style.

While a droplet 102 is shown, and described above with respect to FIG.1, FIGS. 2A-2C, and FIGS. 3A-3B, the foregoing is likewise applicable toadditional droplets, for example, a second droplet and a third droplet.FIG. 4A is a simplified cross sectional view according to an embodimentof a second droplet 122 and a third droplet 124 received at the opticalsurface 104 (e.g., located on the optical surface 104) under surfacewetting control. FIG. 4B is a cross sectional view according to anembodiment, similar to FIG. 4A, but showing movement of the seconddroplet 122 and the third droplet 124 at the optical surface 104 undersurface wetting control. FIG. 4C is a cross sectional view according toan embodiment, similar to FIG. 4B, but showing vibration to expel fluidfrom the second droplet 122 and the third droplet 124 at the opticalsurface 104 under surface wetting control.

In the examples of FIGS. 4A-4C, the second wettability of the secondareas 110A, 110B, 110C of the optical surface 104 can be greater thanthe first wettability of the first areas 108A, 108B of the opticalsurface 104. For example, the second wettability of the second areas110B, 110C of the optical surface 104 is sufficiently greater than thefirst wettability of the first areas 108A, 108B of the optical surfaceto cause at least some movement of the second and third droplets 122,124 from the first areas 108A, 108B to the second areas 110B, 110C. Theexample of FIG. 4A shows second droplet 122 partially received at (e.g.,partially located on) one of the first areas 108A having the firstwettability and partially received at (e.g., partially located on) onethe second areas 110B having the second wettability. Similarly, theexample of FIG. 4A also shows third droplet 124 partially received at(e.g., partially located on) another one of the first areas 108B havingthe first wettability and partially received at (e.g., partially locatedon) another one the second areas 110C having the second wettability.Since the second wettability is greater than the first wettability,notional block arrows are shown in FIG. 4A to depict movement of thesecond droplet 122 from the one of the first areas 108A to one of thesecond areas 110 B, and to depict movement of the third droplet 124 fromanother one of the first areas108B to another one of the second areas110C. Further, comparison of FIG. 4A to FIG. 4B shows that in FIG. 4Bthe second droplet 122 has moved to the one of the second areas 110B,from being partially received at (e.g., partially located on) one of thefirst areas 108A and partially received at (e.g., partially located on)the one of the second areas 110B in FIG. 4A. In FIG. 4B the thirddroplet 124 has moved to another one of the second areas 110C, frombeing partially received at (e.g., partially located on) another one ofthe first areas 108B and partially received at (e.g., partially locatedon) another one of the second areas 110C in FIG. 4A.

For example, FIG. 4C shows the vibrational mode of the optical surface104 having a first extent of vibration (e.g., EXTENT1) at first areas108A, 108B and having a second extent of vibration (e.g., EXTENT2) atone and another one of the second areas 110B, 110C. As shown in theexample of FIG. 4C, the second extent of vibration (e.g., EXTENT2) atone and another one of the second areas 110B, 110C is greater than thefirst extent of vibration (e.g., EXTENT1) at the first areas 108A, 108B.For example, the relatively greater wettability of one and another oneof the second areas 110B, 110C can move the second and third droplets122, 124, where the relatively greater extent of vibration (e.g.,EXTENT2) can expel fluid from the droplet by atomization. For example,regions of greatest wettability (e.g. second areas 110B, 110C) can beplaced at locations of largest vibration amplitude. In the example ofFIG. 4C, notional upward block arrows are used to depict the relativelygreater extent of vibration (e.g., EXTENT2) expelling fluid from thesecond and third droplets 122, 124 by atomization. An added benefit iswhen droplets that are smaller than a given region fall onto thesurface, they will still tend migrate to the locations of largestvibration amplitude due to an acceleration gradient across the droplet.

FIG. 5A is a simplified cross sectional view according to anotherembodiment of the droplet 502 received at the optical surface 504 (e.g.,located on the optical surface 504) under gradient control of surfacewetting. FIG. 5B is a cross sectional view according to an embodiment,similar to FIG. 5A, but showing movement of the droplet 502 at theoptical surface 504 under gradient control of surface wetting. FIG. 5Cis a cross sectional view according to an embodiment, similar to FIG.5B, but showing vibration to expel fluid from the droplet 502 at theoptical surface 504 under gradient control of surface wetting.

A first area 508A having an increasing gradient of wettability in adirection towards second area 510A is shown in the examples of FIGS.5A-5C using an increasingly darkened gradient depiction in the directiontowards second area 510A. Similarly, additional first area 508B havingan increasing gradient of wettability in an additional direction towardssecond area 510A is shown in the examples of FIGS. 5A-5C using anincreasingly darkened gradient depiction in the additional directiontowards second area 510A. The second area 510A is shown in the examplesof FIGS. 5A-5C using cross hatching. The examples of FIGS. 5A-5C showthe increasing wettability gradient patterned arrangement in crosssectional view of the first areas (e.g., first areas 508A, 508B) and thesecond area (e.g., second area 510A). For example, a second area 510Acan be interposed between a pair of members of the first areas (e.g.,pair of first areas 508A, 508B). For example, second area 510A can becentrally arranged between first area 508A and additional first area508B. For example, the first area 508A can have an increasing gradientof wettability in a centrally oriented direction towards second area510A, as shown in the examples of FIGS. 5A-5C using an increasinglydarkened gradient depiction in the centrally oriented direction towardssecond area 510A. Similarly, additional first area 508B can have anincreasing gradient of wettability in an additional centrally orienteddirection towards second area 510A as shown in the examples of FIGS.5A-5C using an increasingly darkened gradient depiction in theadditional centrally oriented direction towards second area 510A. Forexample, the optical surface 504 can have a wettability gradient thatincreases (e.g. increases monotonically) from peripheral areas of theoptical surface 504 (e.g., first area 508A and additional first area508B) towards a central area of the optical surface 504 (e.g., secondarea 510A).

In the examples of FIGS. 5A-5C, the second wettability of the secondarea 510A of the optical surface 504 can be greater than the firstgradient wettability of the first areas 508A, 508B of the opticalsurface 504. For example, the hydrophobic coating can be applied in asuitable gradient manner, for example using inkjet printing, to thefirst areas 508A, 508B so as to limit the wettability of the first areas508A, 508B in a gradient manner. For example, application of thehydrophobic coating to the second area 510A can be avoided, so thatsecond wettability of the second area 510A of the optical surface 504can be greater than the first gradient wettability of the first areas508A, 508B.

The second wettability of the second area 510A of the optical surface504 is sufficiently greater than the first gradient wettability of thefirst areas 508A, 508B of the optical surface 504 to cause at least somemovement of the droplet 502 from the first area 508A to the second area510A. FIG. 5A shows droplet 502 partially received at (e.g., partiallylocated on) the first area 508A having the first gradient wettabilityand partially received at (e.g., partially located on) the second area510A having the second wettability. Since the second wettability isgreater than the first gradient wettability, a notional block arrow isshown in FIG. 5A to depict movement of the droplet 502 from the firstarea 508A to the second area 510 A. Further, comparison of FIG. 5A toFIG. 5B shows that in FIG. 5B the droplet has moved to the second area510A, from being partially received at (e.g., partially located on) thefirst area 508A and partially received at (e.g., partially located on)the second area 510A in FIG. 5A. For example, since the optical surface504 can have a wettability gradient that increases (e.g. increasesmonotonically) from peripheral areas of the optical surface 504 (e.g.,first area 508A and additional first area 508B) towards a central areaof the optical surface 504 (e.g., second area 510A), the droplet 502 canbe moved thereby from peripheral areas of the optical surface 504 (e.g.,from first area 508A) towards the central area of the optical surface504 (e.g., towards second area 510A).

The ultrasonic transducer 106 described above with respect to FIG. 1 canexcite a vibrational mode of the optical surface 504 having a greaterextent of vibration at the second area 510A than at the first area 508A.For example, FIG. 5C shows the vibrational mode of the optical surface504 having a first extent of vibration (e.g., EXTENT1) at the first area508A and having a second extent of vibration (e.g., EXTENT2) at thesecond area 510A. As shown in the example of FIG. 5C, the second extentof vibration (e.g., EXTENT2) at the second area 510A is greater than thefirst extent of vibration (e.g., EXTENT1) at the first area 508A. Forexample, the relatively greater wettability of the second area 510A canmove the droplet 502, where the relatively greater extent of vibration(e.g., EXTENT2) can expel fluid from the droplet by atomization. Forexample, regions of greatest wettability (e.g. second area 510A) can beplaced (e.g., centrally placed) at locations of largest vibrationamplitude. In the example of FIG. 5C, a notional upward block arrow isused to depict the relatively greater extent of vibration (e.g.,EXTENT2) expelling fluid from the droplet 502 by atomization.

FIG. 5D is a cross sectional view according to another embodiment,similar to FIG. 5B, but with first areas 508A, 508B much larger than thedroplet 502 and with a second area 510A much smaller than the droplet502. In some examples, the second area 510A can be an order of magnitudesmaller than the droplet 502 (e.g., at least an order of magnitudesmaller than the droplet 502, or even smaller). In the example of FIG.5D, the first area 508A can have the increasing gradient of wettabilityin the centrally oriented direction towards second area 510A, as shownin FIG. 5D using the increasingly darkened gradient depiction in thecentrally oriented direction towards second area 510A. Similarly,additional first area 508B can have the increasing gradient ofwettability in the additional centrally oriented direction towardssecond area 510A as shown in FIG. 5D using the increasingly darkenedgradient depiction in the additional centrally oriented directiontowards second area 510A. For example, the optical surface 504 shown inFIG. 5D can have the wettability gradient that increases (e.g. increasesmonotonically) from peripheral areas of the optical surface 504 (e.g.,first area 508A and additional first area 508B) towards the central areaof the optical surface 504 (e.g., second area 510A).

In additional other examples, the first areas and/or second areas can besmaller than the droplet (e.g., an order of magnitude smaller than thedroplet, e.g., at least an order of magnitude smaller than the droplet,or smaller). In some examples, respective members of the first areas108A, 108B, 108C, 108D, 108E, 108F, 108G, 108H, 108I, 108J, 108K, 108Lshown in FIG. 1 can be smaller than the droplet 102 (e.g., an order ofmagnitude smaller than the droplet, e.g., at least an order of magnitudesmaller than the droplet, or smaller). In some examples, respectivemembers of the second areas 110A, 110B, 110C, 110D, 110E, 110F, 110G,110H, 110I, 110J, 110K, 110L, 110M can be smaller than the droplet 102(e.g., an order of magnitude smaller than the droplet, e.g., at least anorder of magnitude smaller than the droplet, or smaller).

FIG. 5E is a simplified view similar to what is shown in FIG. 1, butwith first areas 508A, 508B, 508C, 508D, 508E, 508F, 508G, 508H, 508I,508J, 508K, 508L and second areas 510A, 510B, 510C, 510D, 510E, 510F,510G, 510H, 510I, 510J, 510K, 510L, 510M shown much smaller than thedroplet 502 on optical surface 504. Second wettability of the secondareas of the optical surface 504 can be greater than the firstwettability of the first areas. The first areas are shown in the exampleof FIG. 5E using stippling. The second areas are shown in the example ofFIG. 5E using cross hatching.

FIG. 6A is a diagram 600 a of impedance (Ohms in decibels) versusfrequency (logarithmic scale in kilohertz) for an example ultrasonictransducer mechanically coupled to an example optical surface accordingto an embodiment. FIG. 6A shows the example first frequency ofthree-hundred kilohertz for the example ultrasonic transducermechanically coupled to the example optical surface. The example firstfrequency of the example three-hundred kilohertz can correspond to afirst nominal resonance frequency of a first low impedance resonanceextremity 602 in the diagram of FIG. 6A at the first frequency of theexample ultrasonic transducer mechanically coupled to the exampleoptical surface. The example first frequency of three-hundred kilohertzcan correspond to the first nominal resonance frequency of the first lowimpedance resonance extremity 602 that is centered within a firstresonance band “602band”. More broadly, the first frequency is within afirst resonance band “602band”. The first resonance band is definedherein as extending in frequency to plus and minus ten percent of thefirst nominal resonance frequency of the first low impedance resonanceextremity for the ultrasonic transducer mechanically coupled to theoptical surface. For example, with the example first frequency ofthree-hundred kilohertz, the first resonance band extends in frequencyto plus and minus ten percent of the first nominal resonance frequencyof three-hundred kilohertz (e.g. the first resonance band extends infrequency to plus and minus thirty kilohertz from the three-hundredkilohertz, or the first resonance band extends in frequency fromtwo-hundred-and-seventy kilohertz to three-hundred-and-thirtykilohertz).

Further, FIG. 6A shows the example second frequency of twenty-sixkilohertz for the example ultrasonic transducer mechanically coupled tothe example optical surface. The example second frequency of twenty-sixkilohertz corresponds to a second nominal resonance frequency of asecond low impedance resonance extremity 604 in the diagram of FIG. 6Aat the second frequency of the example ultrasonic transducermechanically coupled to the example optical surface. The example secondfrequency of twenty-six kilohertz corresponds to the second nominalresonance frequency of the second low impedance resonance extremity 604that is centered within a second resonance band “604band”. More broadly,the second frequency is within a second resonance band “604band”. Thesecond resonance band is defined herein as extending in frequency toplus and minus ten percent of the second nominal resonance frequency ofthe second low impedance resonance extremity for the ultrasonictransducer mechanically coupled to the optical surface. For example,with the example second frequency of twenty-six kilohertz, the secondresonance band extends in frequency to plus and minus ten percent of thesecond nominal resonance frequency of twenty-six kilohertz (e.g. thesecond resonance band extends in frequency to plus and minus two andsix-tenths kilohertz from the twenty-six kilohertz, or the secondresonance band extends in frequency from twenty-three-and-four-tenthskilohertz to twenty-eight-and-six-tenths kilohertz).

FIG. 6B is a diagram 600 b of example droplet size reduction versusfrequency according to an embodiment. The example of FIG. 6B shows theexample first frequency of the example three-hundred kilohertz for theexample ultrasonic transducer mechanically coupled to the exampleoptical surface. As shown in the example of FIG. 6B, the example firstfrequency 602 of the example three-hundred kilohertz can reduce thedroplet from the first droplet size 606 (e.g., reduce from tenmillimeters in droplet diameter) to the second droplet size 608 (e.g.,reduce to four millimeters in droplet diameter). Further, the example ofFIG. 6B shows the example second frequency 604 of twenty-six kilohertzfor the example ultrasonic transducer mechanically coupled to theexample optical surface. As shown in the example of FIG. 6B, the examplesecond frequency 604 of twenty-six kilohertz can reduce the droplet fromthe second droplet size 608 (e.g., reduce from four millimeters indroplet diameter) to the third droplet size 610 (e.g., reduce toeight-tenths of a millimeter in droplet diameter).

While example manners of implementing the example system 100 forexpelling fluid from a droplet 102 from an optical surface 104 using theultrasonic transducer 106 mechanically coupled to the optical surface104 under wettability control as in FIG. 1, one or more of the elements,processes and/or devices illustrated in FIG. 1 may be combined, divided,re-arranged, omitted, eliminated and/or implemented in any other way.

Further, the example system 100, example optical surface 104, 504,example ultrasonic transducer 106, example first areas 108A, 108B, 108C,108D, 108E, 108F, 108G, 108H, 108I, 108J, 108K, 108L, 508A, examplesecond areas 110A, 110B, 110C, 110D, 110E, 110F, 110G, 110H, 110I, 110J,110K, 110L, 110M, 510A, 510B, example edge of the first area 108AE,example edge of second area 110AE, example signal generator 112, examplefirst signal 114, example first frequency 116, example second signal118, example second frequency 120, example width of first area W108A,example width of second area W110A, example first extent of vibrationEXTENT1, example second extent of vibration EXTENT2, example first lowimpedance resonance extremity 602, example first resonance band 602band,example second low impedance resonance extremity 604, and example secondresonance band 604band of the example of FIG. 1 may be implemented byhardware, software, firmware and/or any combination of hardware,software and/or firmware, and may be implemented by one or more analogor digital circuit(s), logic circuits, programmable processor(s),application specific integrated circuit(s) (ASIC(s)), programmable logicdevice(s) (PLD(s)) and/or field programmable logic device(s) (FPLD(s)).

Further still, the example system 100, example optical surface 104, 504,example ultrasonic transducer 106, example first areas 108A, 108B, 108C,108D, 108E, 108F, 108G, 108H, 108I, 108J, 108K, 108L, 508A, examplesecond areas 110A, 110B, 110C, 110D, 110E, 110F, 110G, 110H, 110I, 110J,110K, 110L, 110M, 510A, 510B, example edge of the first area 108AE,example edge of second area 110AE, example signal generator 112, examplefirst signal 114, example first frequency 116, example second signal118, example second frequency 120, example width of first area W108A,example width of second area W110A, example first extent of vibrationEXTENT1, example second extent of vibration EXTENT2, example first lowimpedance resonance extremity 602, example first resonance band 602band,example second low impedance resonance extremity 604, and example secondresonance band 604band of the example of FIG. 1 may include one or moreelements, processes and/or devices in addition to, or instead of, thoseillustrated in FIG. 1, and/or may include more than one of any or all ofthe illustrated elements, processes and devices.

When reading any of the apparatus or system claims of this patent tocover a purely software and/or firmware implementation, at least one ofthe example system 100, example optical surface 104, 504, exampleultrasonic transducer 106, example first areas 108A, 108B, 108C, 108D,108E, 108F, 108G, 108H, 108I, 108J, 108K, 108L, 508A, example secondareas 110A, 110B, 110C, 110D, 110E, 110F, 110G, 110H, 110I, 110J, 110K,110L, 110M, 510A, 510B, example edge of the first area 108AE, exampleedge of second area 110AE, example signal generator 112, example firstsignal 114, example first frequency 116, example second signal 118,example second frequency 120, example width of first area W108A, examplewidth of second area W110A, example first extent of vibration EXTENT1,example second extent of vibration EXTENT2, example first low impedanceresonance extremity 602, example first resonance band 602band, examplesecond low impedance resonance extremity 604, and example secondresonance band 604band of the example of FIG. 1 is/are hereby expresslydefined to include a tangible computer readable storage device orstorage disk such as a memory, a digital versatile disk (DVD), a compactdisk (CD), a Blu-ray disk, etc. storing the software and/or firmware.

FIGS. 7A-7B show a flowchart representative of example machine readableinstructions that may be executed to implement the example system 100 toexpel fluid from the droplet 102 on the optical surface 104 underwettability control, according to an embodiment as shown in the exampleof FIG. 1. In this example, the machine readable instructions comprise aprogram for execution by a processor, such as the processor 812 shown inthe example processor platform 800 described below in connection withFIG. 8. The program may be embodied in software stored on a tangiblecomputer readable storage medium such as a CD-ROM, a floppy disk, a harddrive, a digital versatile disk (DVD), a Blu-ray disk, or a memoryassociated with the processor 812, but the entire program and/or partsthereof could alternatively be executed by a device other than theprocessor 812 and/or embodied in firmware or dedicated hardware.Further, although the example program is described with reference to theflowchart illustrated in FIGS. 7A-7B, many other methods of implementingthe example system 100 to expel fluid from the droplet 102 on theoptical surface 104 under wettability control may alternatively be used.For example, the order of execution of the blocks may be changed, and/orsome of the blocks described may be changed, eliminated, or combined.

As described above, the example processes of FIGS. 7A-7B may beimplemented using coded instructions (e.g., computer and/or machinereadable instructions) stored on a tangible computer readable storagemedium such as a hard disk drive, a flash memory, a read-only memory(ROM), a compact disk (CD), a digital versatile disk (DVD), a cache, arandom-access memory (RAM) and/or any other storage device or storagedisk in which information is stored for any duration (e.g., for extendedtime periods, permanently, for brief instances, for temporarilybuffering, and/or for caching of the information). As used herein, theterm tangible computer readable storage medium is expressly defined toinclude any type of computer readable storage device and/or storage diskand to exclude propagating signals and to exclude transmission media. Asused herein, “tangible computer readable storage medium” and “tangiblemachine readable storage medium” are used interchangeably. In someexamples, the example processes of FIGS. 7A-7B may be implemented usingcoded instructions (e.g., computer and/or machine readable instructions)stored on a non-transitory computer and/or machine readable medium suchas a hard disk drive, a flash memory, a read-only memory, a compactdisk, a digital versatile disk, a cache, a random-access memory and/orany other storage device or storage disk in which information is storedfor any duration (e.g., for extended time periods, permanently, forbrief instances, for temporarily buffering, and/or for caching of theinformation). As used herein, the term non-transitory computer readablemedium is expressly defined to include any type of computer readablestorage device and/or storage disk and to exclude propagating signalsand to exclude transmission media.

A process flow 700 of FIGS. 7A-7B can begin at block 702. At block 702,the optical surface can receive the first size of the droplet to overlapa first area of the optical surface and a second area of the surface.The first area can have a first wettability for a fluid of the droplet.The second area of the surface can have a second wettability for thefluid, in which the first wettability of the first area of the surfaceis greater than the second wettability of the second area of thesurface. For example, FIG. 2A shows optical surface 104 to receive thefirst size of the droplet 102 to overlap the first area 108A of theoptical surface 104 and the second area 110A of the optical surface 104.

Next, as shown in the example of FIG. 7A, at block 704 there can be atleast some movement of the droplet from the first area of the surface tothe second area of the surface based on the first wettability of thefirst area of the surface being greater than the second wettability ofthe second area of the surface. For example, since the secondwettability is greater than the first wettability, a notional blockarrow is shown in FIG. 2A to depict movement of the droplet 102 from thefirst area 108A to the second area 110 A. Further, comparison of FIG. 2Ato FIG. 2B shows that in FIG. 2B the droplet has moved to the secondarea 110A, from being partially received at (e.g., partially located on)the first area 108A and partially received at (e.g., partially locatedon) the second area 110A in FIG. 2A.

Next, as shown in the example of FIG. 7A, at block 706 the first signalincluding the first frequency can be generated. For example, the signalgenerator 112 shown in the example of FIG. 1 can be used to generate thefirst signal 114 having the first frequency 116. As shown in the exampleof FIG. 1, the signal generator 112 can be coupled with the ultrasonictransducer 106. The ultrasonic transducer 106 can be mechanicallycoupled to the optical surface 104.

Next, as shown in the example of FIG. 7A, at block 708 the ultrasonictransducer can be activated using the first signal. As shown in theexample of FIG. 1, the signal generator 112 can be coupled with theultrasonic transducer 106 to activate the ultrasonic transducer 106using the first signal 114. The first frequency 116 of the first signal114 can be within the first resonant frequency band of the ultrasonictransducer 106 mechanically coupled to the optical surface 104. In someexamples, the first frequency 116 of the first signal 114 can be a firstsweep of frequencies (e.g., a first frequency sweep) within the firstresonant frequency band of the ultrasonic transducer 106 mechanicallycoupled to the optical surface 104.

Next, as shown in the example of FIG. 7A, at block 710 the firstfrequency can excite a vibrational mode of the optical surface having agreater extent of vibration at the second area of the optical surfacethan at the first area of the optical surface. For example, FIG. 2Cshows the vibrational mode of the optical surface 104 having a firstextent of vibration (e.g., EXTENT1) at the first area 108A and having asecond extent of vibration (e.g., EXTENT2) at the second area 110A. Asshown in the example of FIG. 2C, the second extent of vibration (e.g.,EXTENT2) at the second area 110A is greater than the first extent ofvibration (e.g., EXTENT1) at the first area 108A. For example, therelatively greater wettability of the second area 110A can move thedroplet 102, where the relatively greater extent of vibration (e.g.,EXTENT2) can expel fluid from the droplet by atomization.

Next, as shown in the example of FIG. 7A, at block 712 the fluid dropletcan be reduced by atomization from the first size to a second size usingthe first signal having the first frequency. As shown in the example ofFIG. 1, fluid droplet 102 can be reduced by atomization from the firstsize 102A to a second size 102B using the first signal 114 having thefirst frequency 116.

Next, as shown in the example of FIG. 7B, at block 714 the second signalincluding the second frequency can be generated. Next, at block 716 theultrasonic transducer can be activated using the second signal. Thesecond frequency of the second signal can be within a second resonantfrequency band of the ultrasonic transducer mechanically coupled to theoptical surface. The second frequency of the second signal can bedifferent than the first frequency of the first signal. The secondresonant frequency band can be different than the first resonantfrequency band. As shown in the example of FIG. 1, the signal generator112 can be coupled with the ultrasonic transducer 106 to activate theultrasonic transducer 106 using the second signal 118.

Next, as shown in the example of FIG. 7B, at block 718 the secondfrequency can excite a vibrational mode of the optical surface having agreater extent of vibration at the second area of the optical surfacethan at the first area of the optical surface. For example, FIG. 2Cshows the vibrational mode of the optical surface 104 having a firstextent of vibration (e.g., EXTENT1) at the first area 108A and having asecond extent of vibration (e.g., EXTENT2) at the second area 110A. Asshown in the example of FIG. 2C, the second extent of vibration (e.g.,EXTENT2) at the second area 110A is greater than the first extent ofvibration (e.g., EXTENT1) at the first area 108A.

Next, as shown in the example of FIG. 7B, at block 720 the droplet canbe reduced by atomization from the second size to a third size using thesecond signal having the second frequency. As shown in the example ofFIG. 1, fluid droplet 102 can be reduced by atomization from the secondsize 102B to a third size 102C using the second signal 118 having thesecond frequency 120.

Next, at decision block 722 it is determined whether to end the cycle ofexpelling fluid from the optical surface. For example, if a controlinput registered at a time determines that the cycle is not to end atthat time, then flow execution transfers to block 702 shown in FIG. 7A.However, if a control input registered at that time determines that thecycle is to end at that time, then after block 722, the example method700 can end.

FIG. 8 is a block diagram of an example processing platform capable ofexecuting the machine readable instructions of FIGS. 8A-8B to implementthe example system to expel fluid from the droplet under wettabilitycontrol, according to an embodiment as shown in the example of FIG. 1.

The processor platform 800 can be, for example, a server, a personalcomputer, a mobile device (e.g., a cell phone, a smart phone, a tabletsuch as an iPad™), a personal digital assistant (PDA), an Internetappliance, a DVD player, a CD player, a digital video recorder, aBlu-ray player, a gaming console, a personal video recorder, a set topbox, or any other type of computing device.

The processor platform 800 of this example includes a processor 812. Theprocessor 812 of this example is hardware. For example, the processor812 can be implemented by one or more integrated circuits, logiccircuits, microprocessors or controllers from any desired family ormanufacturer. The hardware of processor 812 can be virtualized usingvirtualization such as Virtual Machines and/or containers. The processor812 can implement example signal generator 112, including example firstsignal 114, example first frequency 116, example second signal 118, andexample second frequency 120.

The processor 812 of this example includes a local memory 813 (e.g., acache). The processor 812 of this example is in communication with amain memory including a volatile memory 814 and a nonvolatile memory 816via a bus 818. The volatile memory 814 may be implemented by synchronousdynamic random access memory (SDRAM), dynamic random access memory(DRAM), RAMBUS dynamic random access memory (RDRAM) and/or any othertype of random access memory device. The nonvolatile memory 816 may beimplemented by flash memory and/or any other desired type of memorydevice. Access to the main memory 814, 816 is controlled by a memorycontroller.

The processor platform 800 of this example also includes an interfacecircuit 820. The interface circuit 820 may be implemented by any type ofinterface standard, such as an Ethernet interface, a universal serialbus (USB), and/or a PCI express interface.

In this example, one or more input devices 822 are connected to theinterface circuit 820. The input device(s) 822 permit(s) a user to enterdata and commands into the processor 812. The input device(s) can beimplemented by, for example, an audio sensor, a microphone, a camera(still or video), a keyboard, a button, a mouse, a touchscreen, atrack-pad, a trackball, isopoint and/or a voice recognition system.

One or more output devices 824 are also connected to the interfacecircuit 820 of this example. The output devices 824 can be implemented,for example, by display devices (e.g., a light emitting diode (LED), anorganic light emitting diode (OLED), a liquid crystal display, a cathoderay tube display (CRT), a touchscreen, a tactile output device, a lightemitting diode (LED), a printer and/or speakers). The interface circuit820 of this example, thus, usually includes a graphics driver card, agraphics driver chip or a graphics driver processor.

The interface circuit 820 of this example also includes a communicationdevice such as a transmitter, a receiver, a transceiver, a modem and/ornetwork interface card to facilitate exchange of data with externalmachines (e.g., computing devices of any kind) via a network 826 (e.g.,an Ethernet connection, a digital subscriber line (DSL), a telephoneline, coaxial cable, a cellular telephone system, etc.).

The processor platform 800 of this example also includes one or moremass storage devices 828 for storing software and/or data. Examples ofsuch mass storage devices 828 include floppy disk drives, hard drivedisks, compact disk drives, Blu-ray disk drives, RAID systems, anddigital versatile disk (DVD) drives.

The coded instructions 832 of FIG. 8 may be stored in the mass storagedevice 828, in the volatile memory 814, in the nonvolatile memory 816,and/or on a removable tangible computer readable storage medium such asa CD or DVD.

Modifications are possible in the described examples, and otherimplementations are possible, within the scope of the claims.

What is claimed is:
 1. Apparatus to expel fluid from a droplet on asurface using a transducer mechanically coupled to the surface, theapparatus comprising: a first area of the surface having a firstwettability for the fluid; and a second area of the surface having asecond wettability for the fluid, in which the second wettability of thesecond area of the surface is greater than the first wettability of thefirst area of the surface, and the first area and the second area have apatterned arrangement.
 2. The apparatus of claim 1, wherein thetransducer is configured to excite a vibrational mode of the surfacehaving a greater extent of vibration at the second area than at thefirst area.
 3. The apparatus of claim 1, wherein a first edge of thefirst area is proximate to a second edge of the second area in thepatterned arrangement.
 4. The apparatus of claim 1, wherein: the firstarea is a plurality of first areas; the second area is a plurality ofsecond areas; and the patterned arrangement of the first and secondareas is an alternating arrangement in which a member of the first areasis interposed between a pair of members of the second areas.
 5. Theapparatus of claim 1, wherein: the first area is a plurality of firstareas; the second area is a plurality of second areas; and the patternedarrangement of the first and second areas is an alternating arrangementin which a member of the second areas is interposed between a pair ofmembers of the first areas.
 6. The apparatus of claim 1, wherein: thefirst area is a plurality of first areas; the second area is centrallyarranged between a pair of members of the first areas; and the firstareas have respective increasing gradients of wettability in respectivedirections centrally oriented towards the second area.
 7. The apparatusof claim 1, wherein the second wettability of the second area of thesurface is sufficiently greater than the first wettability of the firstarea of the surface to cause at least some movement of the droplet fromthe first area to the second area.
 8. The apparatus of claim 1, furthercomprising a signal generator configured to generate a first signalhaving a first frequency to reduce the droplet from a first size to asecond size, and to generate a second signal having a second frequencyto reduce the droplet from the second size to a third size.
 9. Theapparatus of claim 8, wherein the first area has a first width dimensionthat is greater than a corresponding width of the second size of thedroplet.
 10. The apparatus of claim 8, wherein the second area has asecond width dimension that is greater than a corresponding width of thesecond size of the droplet.
 11. The apparatus of claim 8, wherein thefirst area has a first width dimension that is greater than acorresponding width of the third size of the droplet.
 12. The apparatusof claim 8, wherein the second area has a second width dimension that isgreater than a corresponding width of the third size of the droplet. 13.The apparatus of claim 8, wherein the first frequency is higher than thesecond frequency.
 14. The apparatus of claim 8, wherein the firstfrequency is within a first resonant frequency band of the transducer,and the second frequency is within a second resonant frequency band ofthe transducer.
 15. Apparatus to expel fluid of a droplet from a surfaceusing a transducer mechanically coupled to the surface, the apparatuscomprising: first and second adjacent areas of the surface in which thedroplet overlaps the first and second areas of the surface, and thefirst area has a first wettability that is greater than a secondwettability of the second area; and a signal generator configured togenerate a signal having a frequency to reduce a size of the droplet.16. The apparatus of claim 15, wherein the frequency of the signalgenerator is to excite a vibrational mode of the surface having agreater extent of vibration at the second area than at the first area.